ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 45 



abutting on the ovaries. The homologue of the funiculus is short 

 and quite free, its tip serving for the development of buds. 



Vitality of Fresli-water Polyzoa.* — Dr. H. Allen calls attention 

 to tenacity of life as exhibited in a fresh-water Plumatella (P. vesi- 

 cularia Leidy). The leaf of the lily on which the colony had fixed 

 itself, had been, by accident, removed from the water of the aquarium, 

 and had been exposed for sixteen hours to the air. The animals had 

 apparently become dry, and the colony itself barely visible to the 

 unaided eye. Upon being again immersed (in water that chanced to 

 be impregnated with iron-rust), the animals revived and flourished for 

 two weeks, at the end of which time they perished from the effects of 

 the decay of the leaf on which they were growing. 



The following facts are of interest in this connection. First, that 

 in these animals, relatively high in organization, aeration may go on 

 for a number of hours by means of the retracted tentacles in the small 

 amount of water contained within the cells. Second, that the presence 

 of oxide of iron in the water does not interfere with the growth of the 

 animals. And third, that the genus Plumatella may be found to 

 resemble other mollusc-like creatures, not only in their plan of 

 organization, but in their habits of sustaining life for long periods 

 after removal of the animals from water. The last-named fact may 

 possibly enter into questions of geographical distribution of this and 

 allied forms. 



Observations on Living Polyzoa.t — Mr. C. M. Maplestone de- 

 scribes observations made upon specimens either dredged, obtained 

 from old piles, drawn up from the pier, or washed up on the beach. 

 While some of those dredged, or carefully collected from the piles, 

 and immediately transferred into bottles of sea-water, never expanded, 

 many of those found on the beach and not expected to be alive did so. 

 On filling a large bag with Polyzoa, and making a preliminary 

 examination with a Coddington lens in the evening, some of the 

 animals were found to be moving within the cells, and on transferring 

 them to the zoophyte trough several species expanded. The author 

 thinks it useful to mention this, as it may not be generally known 

 that if Polyzoa are gathered soon after being washed up on the beach, 

 or hefm-e getting dry, and are afterwards kept merely damp, there is a 

 probability of finding them living, and he has often since found 

 them so. 



Arthropoda. 

 a. Insecta, 



Polar Cells of Insects.^ — M. E. G. Balbiani has followed all the 

 phases of the transformation of the polar cells in a Chironomus, and 

 considers himself to be in a position to determine the precise signifi- 

 cance of these elements. After tracing the process of development 

 from tbeir first appearance to the moment when the larva is hatched, 



* Proc. Acad. Nat. Sci. Philad., 1882, pp. 223-4. 



t Trans, and Proc. Eoyal Soc. of Victoria, xviii. (1882) pp. 48-51 (1 pi.)- 



j Comptes Kcndus, xcv. (1882) pp. 927-9. 



